diff --git a/docs/doc-requirements.txt b/docs/doc-requirements.txt
index 660b872..2d33eb9 100644
--- a/docs/doc-requirements.txt
+++ b/docs/doc-requirements.txt
@@ -1,2 +1,3 @@
 lxml
 sphinx
+pip>=1.5  # this is mostly for RTD, which builds us with old pip